Battery charger with power dissipation control

摘要

A battery charger uses an unregulated DC transformer (100) as a power source for charging a battery pack (101) through a pass device (104). A charger controller (150) instantaneously computes a desired charging current value for maximizing the charging efficiency of the battery charger based on the present voltage of the battery pack (101), ambient temperature data received from a thermistor (121), and charging rates and other charging parameters received from a data-storage device (123) in the battery pack. The charger controller sends the calculated desired charging current information to a power controller (103). The power controller (103) monitors the instantaneous power dissipation of the pass device (104) and scales the desired charging current value to prevent excessive power dissipation in the pass device (104). By allowing the charging voltage to vary and dynamically adjusting the charging current, various types of batteries can be recharged without the use of an expensive tracking regulator.